1. Field of the Invention
The invention relates generally to a conveyor belt cleaner and more particularly to a resiliently biased shock-absorbing belt cleaner for scraping objectionable foreign materials from the surface of power driven conveyor belts.
2. Description of the Prior Art
The prior art discloses many types of mechanical cleaning assemblies mounted beneath the return run or strand of a conveyor belt for scraping or wiping objectionable foreign materials which had adhered to the belt. Early belt cleaners employed leaf springs to resiliently bias the wiper or scraper blades toward the conveyor belt and the blades were normally arranged in echelon fashion, in a single row, to provide an overlapping effect. Later patents teach arranging a plurality of scraper blades in staggered rows in an overlapping fashion so as to achieve improved cleaning efficiency without interference between adjacent blades.
U.S. Pat. No. 3,342,312, teaches a conveyor belt cleaner which employs a plurality of independently operable scraper blades which are biased toward the return run of the belt by a plurality of torsion arm spring members. Later patents teach other forms of individually operable scraper blade arms biased to swing about a pivot point and urge the scraper blade into scraping contact with the conveyor belt by means of various types of spring members.
U.S. Pat. No. 3,656,610, which is assigned to the Assignee of the present invention, teaches a plurality of independently operable torsion spring wiper blade assemblies mounted on a support structure by means of a resilient mounting assembly which absorbes vibration and shock to minimize fatigue and breakage of the spring arms. The spring arms of this patent are torsion springs having elongated slender portions with a circular cross-section. They are made from a single piece of spring steel and the rear end is bent back upon itself to form an elongated eyelet. The patent teaches that a resilient block of elastomeric material can be secured to the arm by passing a threaded bolt through a hole in the resilient block and through the eyelet for securing the assembly to the support.
Other prior are patents teach conveyor belt cleaner assemblies wherein individually operable scraper blade arms are biased to swing about a pivot axis and urge the wiper blades into contact with a conveyor belt by means of individual elastomeric spring members associated with each of the arms. Furthermore, the prior art teaches that a plurality of wiper blade assemblies which are not individually operable may be provided with relatively flat portions at the support-engaging end thereof and rigidly bolted to the support through the flat portion.
While the pior art has shown the use of a resilient block of elastomeric material used to mount the support-engaging end of a slender elongated torsion arm having a circular cross-section, it has been found that the generally circular nature of the arm tends to push down through and eventually destroy the effectiveness of the elastomeric block due to the uneven distribution of the load experienced by the arm.
It has also been found that the use of apertures or eyelets in the support-engaging end of the arms structurally weakens the arm and often leads to breakage at the point of the apertures. Furthermore, the use of an apertured arm and a block of elastomeric material having apertures therethrough so that the block may be connected to the arm through the apertures also tends to structurally weaken the elastomeric block and cause premature deterioration of the elastomeric material.
Furthermore, while compression springs have been employed in the prior art to bias the arm so as to urge the scraper blades towards the conveyor belt, the arms have not been shaped so as to more evenly distribute the load experienced by the arm over the spring assembly so as to prolong the life of the scraper blade assemblies.
The elongated arms used in the scraper blade assemblies of the prior art are normally leaf springs or torsion arms and they are seldom formed from rod-like spring material or from any type of non-spring-type material which could greatly increase their resistance to breakage. The United States patents listed below are cited herein as being typical of the prior art generally found in this field: U.S. Pat. Nos. 2,393,724; 2,794,540; 3,315,794; 3,342,312; 3,504,786; 3,598,231; 3,656,610 and 3,674,131.
The present invention provides an improved means for absorbing shock and for biasing the scraper blades toward the conveyor belt while more evenly distributing the load experienced by the arm over the biasing means so as to prolong the life of the arm and the life of the biasing means.